An interdigital transducer, interdigitized transducer, or interdigitated transducer, is a device or sensor which typically consists of two interlocking comb-shaped metallic coatings or structures that have been applied to a piezoelectric substrate, such as quartz, lithium niobate, or piezoelectric ceramics, for the purpose of converting electrical or electromagnetic energy (e.g., microwaves) into acoustic energy (e.g., surface acoustic waves (SAW)) or vice versa. Interdigital transducers may be used to generate and receive ultrasonic surface waves for the purpose of inspecting the surface condition of a particular item or for measuring its acoustic properties.
Currently, there are no known effective means for transferring surface waves generated by a flat interdigital transducer to a curved, contoured, or otherwise non-flat surface of an object. A custom-designed curved interdigital transducer may be fabricated for use on a curved surface of a part being inspected. However, creating complex contoured interdigital transducers is difficult and increases manufacturing costs considerably. Furthermore, a custom-designed interdigital transducer or sensor is only compatible with the specific contoured part or surface for which the sensor was originally designed. Accordingly, there is a need for a means by which flat interdigital transducers or sensors may be easily and inexpensively adapted for use with curved or contoured items that are to be inspected.